Beowulf with Gigabit Ethernet

Øystein Gran Larsen gran at
Fri Jan 11 05:16:50 EST 2002

Patrick Geoffray wrote:

> Hi Øystein,
> Øystein Gran Larsen wrote:
> > Check our ScaMPI datasheet at
> > It uses ping-pong performance to illustrate the performance of SCI, Myrinet and Ethernets.
> Which Myrinet hardware are you using in your test ? It looks like old
> 1.28 Gb/s interfaces not sold since quite a while (more than a year).
> If it's the 2 Gb/s interfaces, the PCI is obviously the bottleneck
> (the MPI curve caps normally at 240 MB/s with this equipment on a good
> PCI 64/66).
> You may want to precise in your document the Myrinet model and the PCI
> characteristics of the test machines, and eventually the fact that the
> Myrinet equipment used is no longer available. This is required for a
> fair interpretation.
> Regards
> ----------------------------------------------------------
> |   Patrick Geoffray, Ph.D.      patrick at
> |   Myricom, Inc.     
> |   Cell:  865-389-8852          685 Emory Valley Rd (B)
> |   Phone: 865-425-0978          Oak Ridge, TN 37830
> ----------------------------------------------------------
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Hi Patrick,

I agree that the data sheet could be more detailed. As far as I have been able
to uncover the Myrinet card in question was a PCI64B with 4MB SRAM and 2Gbit/s
link speed. The performance measurements were performed outside Scali and made
available to us.

>From time to time we try to find performance numbers of this kind for different
interconnects, but we have so far not been able to find any such (official)
results for Myrinet products. If they were available it could be expected of us
to use them when we try to compare products. In their absence we must rely on
and trust helpful individuals that have access to Myrinet systems for the numbers.
If you can direct us at an official resource with such numbers we would be very

By the way, this type of performance numbers for the latest release of our
software is not on our web site yet, but it's on its way. The numbers for previous
releases can be found in the performance section on


Øystein Gran Larsen, Dr.Scient mailto:gran at Tel:+47 2262-8982
       MPI·SCI=HPC -- Scalable Linux Systems --
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